1. Field of the Invention
The present invention relates to processing test measurements collected from a multi-cylinder internal combustion engine to yield diagnostic results, and more specifically to a system for processing cold-test data collected from an internal combustion engine for optimum determination of engine condition.
2. Related Art
Testing newly manufactured internal combustion engines is often performed by "cold test" (i.e., cranking the engine at a prescribed speed via an external motor, without spark or fuel). Measurements (such as electrical signals of an engine parameter, e.g., oil pressure, intake exhaust pressure, crankshaft torque, etc. ) are then taken from the engine and compared to a set of known rules (e.g., waveforms) that have been established to represent a properly running engine.
When a particular engine part is faulty, it will typically produce a symptom that does not match the rule, thereby signifying it is not functioning properly. For example, the torque waveform (analog representation) of an engine being monitored typically produces a signature that corresponds to compression in a particular cylinder. If that signature does not exist, it suggests that something is malfunctioning (e.g., a spark plug is missing or piston ring is missing, etc.).
The problem associated with performing analysis by viewing waveforms is that rules must be established that indicate what is a malfunctioning condition. There may be several rules needed to identify a single problem and then several more rules developed to diagnose the problem. Additionally, the waveform from one problem (e.g., missing piston ring) might look exactly the same as a distinct problem (e.g., missing spark plug), making it very difficult to distinguish two different problems that have like symptoms. As a result it is necessary to perform further time consuming and intricate tests to isolate and identify the underlying fault. Therefore, there is a need to precisely distinguish faults that display very similar symptoms without performing additional time consuming tests.
Additionally, if a new fault arises that was not considered, a rule may not exist to identify this "fault" as a true problem. As a result defects in engines will be missed and as a consequence can create significant post manufacturing costs. Thus, there is a need to be able to detect faults that deviate from any observed and known rule.
Furthermore, it is time consuming to develop a conventional system for testing an engine and performing diagnostics. For instance, it typically takes several months to develop a conventional engine analysis system. The mason is that a significant number of "rules" must be generated to match a specific engine design. Additionally, if the engine is altered or redesigned slightly and a data base is already established, it may take several weeks to modify the data base. Therefore, there is a need to reduce the time it takes to develop an engine analysis system for diagnostic purposes.